Modification of polymers having aromatic groups through formation of boronic ester groups

Abstract

The C—H bond of pendant aromatic groups such as commercial polystyrenes with three types of tacticities (syndiotactic, isotactic, atactic) undergo catalyzed functionalization with boron reagents. A boronic ester group formed on the polymer in the polystyrene was further converted to hydroxy and arene via oxidation and coupling reactions, respectively. These functionalizations proceeded without significantly affecting the molecular weight of starting polymer and the functional concentrations could be easily controlled by changing the ratio of boron reagent to monomer unit.

Description

RELATED APPLICATION DATA[0001]This Application claims priority from U.S. Provisional Application Ser. No. 60 / 921,459, filed 2 Apr. 2007.GOVERNMENT INTEREST[0002]The present technology was developed free of any Government fundingBACKGROUND OF THE INVENTION[0003]The present invention relates to polymers, polymer chemistry and the modification of properties of polymers by chemical reactions with the polymer.Polyolefins are the most ubiquitous commercial polymer in the world owing to their unique chemical and physical properties, processability, and low production cost. Controlled introduction of specific functionality into nonpolar polyolefins can yield a new class of polymeric materials with enhanced abilities such as adhesion to polar surfaces. Synthesis of such a material (i.e., a functionalized polyolefin), however, remains an important challenge in polymer chemistry. Syndiotactic polystyrene (sPS) is a good example of a stereoregular polyolefin that needs further improvement. sPS ...

AI Technical Summary

Benefits of technology

[0006]The C—H bond of commercial or proprietary polymers having either pendant or backbone aromatic groups such as polystyrenes or polysulfones can undergo catalyzed (e.g., Ir-catalyzed) functionalization of with three types of tacticities (syndiotactic, isotactic, atactic) with boron reagents. The boronic ester group formed on the aromatic group on the polymer (e.g., polystyrene) can be further converted to hydroxy (OH) and functionalized arene (e.g., —C6H4-Z, where Z=silane, siloxy, halide

Problems solved by technology

Synthesis of such a material (i.e., a functionalized polyolefin), however, remains an important challenge in polymer chemistry.

Despite these physical properties, sPS has drawbacks that must be overcome if it is to have wide commercial application.

These drawbacks are (a) an excessively high melt processing temperature (>300° C.) that is close to the polymer degradation temperature, (b) poor compatibility with polar materials owing to lack of functionality, and (c) poor impact strength.

Unfortunately, as with other transition metal-catalyzed stereospecific olefins polymerizations, syndiospecific copolymerization of styrene with functionalized styrenes generated polymers with significantly lower molecular weights and/or lower yields compared to those afforded by styrene homopolymerization.

Most postfunctionalizatio

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